Faultline, or subgroup formation based on the alignment of diversity attributes, can cause conflicts and low coordination in diverse teams. While researchers understand the importance of faultlines in team process and negotiations, current computational faultline measures are highly vulnerable to subjective weight assignment of diversity attributes. Therefore, there is limited understanding of which diversity attributes have more impact on faultline formation. In this paper we report 1) a pilot study illustrating the susceptibility of the current faultline measures to subjective evaluations, and 2) an online study illustrating how people’s surface (e.g. age, gender, race) and deep (e.g. personality, cultural norms) level diversity attributes impact their preference and selection of team members, as a proxy of faultline formation. We find while various surface and deep-level attributes predict selection of members, most of these attributes are highly correlated with members’ age, suggesting the importance of this attribute. We discuss future directions for faultline measures with objective rescaling of diversity weights.